Some digital printers write an electrostatic latent image on a photoconductor drum with a laser beam. In areas where the beam contacts the photoconductor drum, the electric charge on the surface of the photoconductor drum is cancelled. In the next stage of printing, ink or toner is provided to the surface of the drum to develop the latent image. The ink is then mechanically rolled off the photoconductor drum's surface onto either a printing medium or an intermediary surface.
Generally, the laser beam is directed to the photoconductor drum's surface with a mirror or prism that adjusts for inconsistent rotary speeds of the photoconductor. The positioning of the mirror is timed to the photoconductor drum's rotary speed to form an accurate latent image and thereby an accurate printed image on the printing medium.